My earlier U.S Pat. No. 3,965,221 describes apparatus for mixing liquid fuel and air in a constant fuel/air ratio as the throttle of an engine is moved. Fuel is injected into the upstream portion of a passage that has a throat, while air moves through the passage and mixes with the fuel to flow into the manifold of the engine. A moveable wall which moves toward and away from a first stationary wall to vary the cross-sectional area of the passage, holds a needle. The needle has a long tapered end that fits into a fuel-supply tube mounted on the stationary wall. As the moveable wall and needle move away from the stationary wall, the needle progressively opens the end of the fuel-supply tube, to allow an increasing fuel flow into the passage as the cross-sectional area of the passage increases.
In practice, it is difficult to accurately control fuel flow into the passage by a needle that progressively withdraws from the fuel-supply tube. A variable fluid supply device of simple but accurately variable capability, would be of value.
In the above-mentioned patent, the moveable wall is moved by an elongated straight rod that moves in a straight line toward and. away from the stationary wall. In engines, a throttle lever usually pivots, and it can require a relatively complex linkage to connect a pivoting throttle lever to a rod that moves in a straight line, without applying side loads that would tend to tilt the moveable wall. A simple mechanism for moving the moveable wall without applying forces that would skew or tilt it, would be of value.
In accordance with one embodiment of the present invention, an apparatus is provided for supplying a substantially constant fuel/air ratio to an engine manifold while varying the amount of air as the engine throttle is moved, which includes a fuel supply tube that more accurately varies the amount of supplied fuel in a simple construction. The amount of air flowing through a passage in a frame, is varied by moving a moveable wall on one side of the passage toward and away from a first stationary wall at an opposite second side of the passage. The moveable wall has a bore in it, and the fuel supply tube extends through the bore and across the passage and is fixed to the stationary wall. The tube has numerous aperture portions which are blocked by a seal on the moveable wall. As the moveable wall moves away from the stationary wall, aperture portions are progressively uncovered to inject progressively more fuel into the passage.
A lever means is provided to couple the engine throttle to the moveable wall in a linkage with a minimum number of links. The lever is pivotally mounted on the frame and has an end pivotally coupled to the moveable wall. In one arrangement, the moveable wall moves along an arc of a circle and the lever end is directly pivotally connected to the moveable wall. In another arrangement, the lever end has a slot that can slide relative to the moveable wall while pivoting relative to it.